[R] problem with "nls" function

Carl Witthoft carl at witthoft.com
Wed Jan 27 23:30:26 CET 2010


<quote>
From: hammadi jbeli <hammadi.jbeli_at_gmail.com>
Date: Tue, 26 Jan 2010 23:40:47 +0100


I have used R formulation style and I found this in some R documentations.
</quote>

Sorry, that makes no sense.   I would recommend you go back to your 
original dataset and pick a very small subset of it--with only 2 
variables, for example.  Then try running nls on that, so at least your 
code line will be a manageable size.

Also, as people regularly remind me :-), post a *small* but reproducible 
  data set so we can see what sort of stuff you're feeding into these 
functions.
{like, say,
L.minor.m1<-nls(Y~a_1_1*D_1+a_1_2*(exp(-gamma_1_F*stdS*(s_F-c_1_F)), 
start=list(a_1_1=0.0593,a_2_1=-0.0822),trace=TRUE) }

Tho' I tend to suspect an attempt to fit that many independent 
exp(gamma)'s is doomed to failure.  If you can explain what the 
underlying data represent, there may be a better, and vectorized, way to 
find a fit function.


Carl



More information about the R-help mailing list